java文字识别技术

java文字识别程序的关键是寻找一个可以调用的OCR引擎。tesseract-ocr就是一个这样的OCR引擎，在1985年到1995年由HP实验室开发，现在在Google。tesseract-ocr 3.0发布，支持中文。不过tesseract-ocr 3.0不是图形化界面的客户端，别人写的FreeOCR图形化客户端还不支持导入新的 3.0 traineddata。但这标志着，现在有自由的中文OCR软件了。

java中使用tesseract-ocr3.01的步骤如下：

1.下载安装tesseract-ocr-setup-3.01-1.exe（3.0以上版本才增加了中文识别）

2.在安装向导中可以选择需要下载的语言包。

3.到网上搜索下载java图形处理所需的2个包：jai_imageio-1.1-alpha.jar，swingx-1.6.1.jar

4.java程序清单：

ImageIOHelper 类：

import java.awt.image.BufferedImage;  
import java.io.File;  
import java.io.IOException;  
import java.util.Iterator;  
import java.util.Locale;  
  
import javax.imageio.IIOImage;  
import javax.imageio.ImageIO;  
import javax.imageio.ImageReader;  
import javax.imageio.ImageWriteParam;  
import javax.imageio.ImageWriter;  
import javax.imageio.metadata.IIOMetadata;  
import javax.imageio.stream.ImageInputStream;  
import javax.imageio.stream.ImageOutputStream;  
  
import com.sun.media.imageio.plugins.tiff.TIFFImageWriteParam;  
  
public class ImageIOHelper {    
        
    public static File createImage(File imageFile, String imageFormat) {    
        File tempFile = null;    
        try {    
            Iterator readers = ImageIO.getImageReadersByFormatName(imageFormat);    
            ImageReader reader = readers.next();    
            
            ImageInputStream iis = ImageIO.createImageInputStream(imageFile);    
            reader.setInput(iis);    
            //Read the stream metadata    
            IIOMetadata streamMetadata = reader.getStreamMetadata();    
                
            //Set up the writeParam    
            TIFFImageWriteParam tiffWriteParam = new TIFFImageWriteParam(Locale.CHINESE);    
            tiffWriteParam.setCompressionMode(ImageWriteParam.MODE_DISABLED);    
                
            //Get tif writer and set output to file    
            Iterator writers = ImageIO.getImageWritersByFormatName("tiff");    
            ImageWriter writer = writers.next();    
                
            BufferedImage bi = reader.read(0);    
            IIOImage image = new IIOImage(bi,null,reader.getImageMetadata(0));    
            tempFile = tempImageFile(imageFile);    
            ImageOutputStream ios = ImageIO.createImageOutputStream(tempFile);    
            writer.setOutput(ios);    
            writer.write(streamMetadata, image, tiffWriteParam);    
            ios.close();    
                
            writer.dispose();    
            reader.dispose();    
                
        } catch (IOException e) {    
            e.printStackTrace();    
        }    
        return tempFile;    
    }    
    
    private static File tempImageFile(File imageFile) {    
        String path = imageFile.getPath();    
        StringBuffer strB = new StringBuffer(path);    
        strB.insert(path.lastIndexOf('.'),0);    
        return new File(strB.toString().replaceFirst("(?<=//.)(//w+)$", "tif"));    
    }    
    
} 

OCR 类：

package com.hhp.util;  
  
import java.io.BufferedReader;    
import java.io.File;    
import java.io.FileInputStream;    
import java.io.InputStreamReader;    
import java.util.ArrayList;    
import java.util.List;    
import org.jdesktop.swingx.util.OS;    
    
public class OCR {    
    private final String LANG_OPTION = "-l";  //英文字母小写l，并非数字1    
    private final String EOL = System.getProperty("line.separator");    
    private String tessPath = "C://Program Files (x86)//Tesseract-OCR";    
    //private String tessPath = new File("tesseract").getAbsolutePath();    
        
    public String recognizeText(File imageFile,String imageFormat)throws Exception{    
        File tempImage = ImageIOHelper.createImage(imageFile,imageFormat);    
        File outputFile = new File(imageFile.getParentFile(),"output");    
        StringBuffer strB = new StringBuffer();    
        List cmd = new ArrayList();    
        if(OS.isWindowsXP()){    
            cmd.add(tessPath+"//tesseract");    
        }else if(OS.isLinux()){    
            cmd.add("tesseract");    
        }else{    
            cmd.add(tessPath+"//tesseract");    
        }    
        cmd.add("");    
        cmd.add(outputFile.getName());    
        cmd.add(LANG_OPTION);    
        cmd.add("chi_sim");    
        //cmd.add("eng");    
            
        ProcessBuilder pb = new ProcessBuilder();    
        pb.directory(imageFile.getParentFile());    
            
        cmd.set(1, tempImage.getName());    
        pb.command(cmd);    
        pb.redirectErrorStream(true);    
            
        Process process = pb.start();    
        //tesseract.exe 1.jpg 1 -l chi_sim    
        int w = process.waitFor();    
            
        //删除临时正在工作文件    
        tempImage.delete();    
            
        if(w==0){    
            BufferedReader in = new BufferedReader(new InputStreamReader(new FileInputStream(outputFile.getAbsolutePath()+".txt"),"UTF-8"));    
                
            String str;    
            while((str = in.readLine())!=null){    
                strB.append(str).append(EOL);    
            }    
            in.close();    
        }else{    
            String msg;    
            switch(w){    
                case 1:    
                    msg = "Errors accessing files.There may be spaces in your image's filename.";    
                    break;    
                case 29:    
                    msg = "Cannot recongnize the image or its selected region.";    
                    break;    
                case 31:    
                    msg = "Unsupported image format.";    
                    break;    
                default:    
                    msg = "Errors occurred.";    
            }    
            tempImage.delete();    
            throw new RuntimeException(msg);    
        }    
        new File(outputFile.getAbsolutePath()+".txt").delete();    
        return strB.toString();    
    }    
}

测试类TestOCR ：

import java.io.File;  
import java.io.IOException;  
  
import com.hhp.util.OCR;  
  
public class OcrTest {  
  
 public static void main(String[] args) {  
        String path = "C://temp//OCRcode//4.png";       
        System.out.println("ORC Test Begin......");  
        try {       
            String valCode = new OCR().recognizeText(new File(path), "png");       
            System.out.println(valCode);       
        } catch (IOException e) {       
            e.printStackTrace();       
        } catch (Exception e) {    
            e.printStackTrace();    
        }         
        System.out.println("ORC Test End......");  
    }    
  
}